Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Stronghold Rats

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Stronghold Rats deals combat damage to a player, each player discards a card.

Midnight Scavengers

When Midnight Scavengers enters, you may return target creature card with mana value 3 or less from your graveyard to your hand.
(Melds with Graf Rats.)

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Graf Rats

At the beginning of combat on your turn, if you both own and control Graf Rats and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.

Swamp

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Mountain

Blood Divination

As an additional cost to cast this spell, sacrifice a creature.
Draw three cards.

Pestilence Rats

Pestilence Rats's power is equal to the number of other Rats on the battlefield. (For example, as long as there are two other Rats on the battlefield, Pestilence Rats's power and toughness are 2/3.)

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Carnage

Carnage deals 3 damage to target opponent. That player discards two cards.

Carnival

Carnival deals 1 damage to target creature or planeswalker and 1 damage to that permanent's controller.

Carnival // Carnage

Altar's Reap

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Earsplitting Rats

When Earsplitting Rats enters, each player discards a card.
Discard a card: Regenerate Earsplitting Rats.

Hellhole Rats

Haste
When Hellhole Rats enters, target player discards a card. Hellhole Rats deals damage to that player equal to that card's mana value.